176
FXUS66 KLOX 251605
AFDLOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
905 AM PDT FRI APR 25 2025
SYNOPSIS
25/843 AM.
A DEEP MARINE LAYER AND STRONG ONSHORE FLOW WILL MAKE FOR ANOTHER
COOL DAY TODAY, THOUGH MORNING CLOUDS WILL GIVE WAY TO PARTLY
CLOUDY SKIES IN MOST AREAS. AN UPPER LOW AND FRONTAL SYSTEM WILL
BRING SOME RAIN TO THE AREA SATURDAY WITH SNOW ABOVE 5000 FEET. IT
WILL BE VERY COOL ON SATURDAY. AFTER THE UPPER LOW MOVES EAST OF
THE REGION, DRY WEATHER IS EXPECTED SUNDAY THROUGH NEXT WEEK WITH
A WARMING TREND.
SHORT TERM (TDY-SUN)
25/905 AM.
***UPDATE***
MARINE LAYER HAS RISEN TO 6000 FEET THIS MORNING WITH A SLIGHT
INCREASE IN ONSHORE FLOW. THERE HAVE BEEN A FEW REPORTS OF DRIZZLE
IN THE FOOTHILLS MOSTLY ABOVE 2000 FEET ELEVATION AND THIS MAY
CONTINUE INTO EARLY AFTERNOON. IN OTHER AREAS THOUGH SKIES HAVE OR
WILL EVENTUALLY BECOME PARTLY CLOUDY WITH SIMILARLY COOL
TEMPERATURES AS YESTERDAY.
NO SIGNIFICANT CHANGES IN THE FORECAST FOR SATURDAY. IF ANYTHING
RAIN CHANCES HAVE INCREASED AREA-WIDE TO NEAR 100% WITH THE
POSSIBLE EXCEPTION OF THE ANTELOPE VALLEY BUT EVEN THERE MOST
AREAS SHOULD SEE AT LEAST SOME SPRINKLES. SOME OF THE MODEL
SOLUTIONS ARE DROPPING THE LOW A LITTLE FARTHER SOUTH, THOUGH BOTH
DETERMINISTIC SOLUTIONS ARE ABOUT THE SAME AS YESTERDAY AND THE
OVERNIGHT ENSEMBLES ARE STILL SOLIDLY CLUSTERED BETWEEN 0.2 AND
0.4", HIGHEST NORTH OF PT CONCEPTION. WILL SEE WHAT THE LATEST HI
RES MODELS AND ENSEMBLES COME IN WITH TODAY MOST LIKELY ANY
CHANCES WILL BE VERY MINOR. TIMING IS FAIRLY SIMILAR AS WELL,
EXCEPT WITH THE UPPER LOW PIVOTING SLIGHTLY THIS IS CAUSING THE
SHOWERS COME IN FROM A MORE SOUTHWESTERLY DIRECTION, WHICH MAY
RESULT IN A SLIGHTLY LATER ARRIVAL ALONG THE CENTRAL COAST AROUND
3-6AM, BUT SOUTH OF PT CONCEPTION SHOWERS SHOULD STILL BE
BEGINNING BETWEEN 5 AND 9AM.
***FROM PREVIOUS DISCUSSION***
AN UPPER LOW LOCATED ABOUT 350 NM W OF EUREKA EARLY THIS MORNING
WILL DROP SLOWLY SOUTHWARD TODAY, REACHING A POSITION ABOUT 400 NM
W OF PT. CONCEPTION LATE THIS AFTERNOON. IT WILL THEN TRACK
EASTWARD, REACHING THE WEST COAST OF SBA OR SOUTHERN SAN LUIS
OBISPO COUNTY LATE SAT MORNING, THEN LIFT EAST-NORTHEASTWARD INTO
THE SOUTHERN SAN JOAQUIN VALLEY LATE SAT AFTERNOON.
CLOUDS WILL INCREASE ACROSS THE REGION TONIGHT. MODELS SHOW AN
ORGANIZES FRONTAL SYSTEM WITH SURFACE FEATURE ASSOCIATED WITH THE
UPPER LOW. RAIN WILL BECOME LIKELY ACROSS SLO AND SBA COUNTIES
LATE TONIGHT, WITH A CHANCE OF RAIN AS FAR SOUTH AS VENTURA COUNTY
BY MORNING. RAIN IS EXPECTED ACROSS THE REGION SAT, MAINLY IN THE
MORNING ACROSS SLO AND SBA COUNTIES, AND FROM LATE MORNING
THROUGH THE AFTERNOON ACROSS VTU AND L.A. COUNTIES. THE 06Z WRF
ACTUALLY KEEPS THE BULK OF THE RAIN TO THE SOUTH OF SLO COUNTY,
WHICH IS A NEW DEVELOPMENT. ALTHOUGH THAT IS NOT SUPPORTED BY THE
EC OR GFS, IT WILL INTERESTING TO SEE IF THAT TREND CONTINUES
ON THE 12Z RUN.
THERE WILL BE INCREASING INSTABILITY ON SAT, AND THERE IS A SLIGHT
CHANCE OF THUNDERSTORMS IN SBA AND SLO COUNTIES AND IN THE NORTHERN
MOUNTAINS OF L.A. AND VTU COUNTIES IN THE AFTERNOON. DEPENDING
UPON THE EVOLUTION OF THE FRONT, THE SLIGHT CHANCE OF
THUNDERSTORMS MAY HAVE TO BE EXTENDED SOUTHWARD INTO COASTAL AND
VALLEY AREAS OF VTU AND L.A. COUNTIES.
AS THE UPPER LOW PULLS TO THE NORTHEAST OF THE REGION SAT NIGHT,
THE THREAT OF RAIN WILL END, MOSTLY BEFORE MIDNIGHT, BUT SKIES
SHOULD REMAIN PARTLY TO MOSTLY CLOUDY OVERNIGHT INTO SUN MORNING.
SATURDAY WILL BE AN UNUSUALLY COLD DAY FOR LATE APRIL IN
SOUTHWESTERN CALIFORNIA, WITH MAX TEMPS 10 TO 20 DEGREES BELOW
NORMAL IN MOST AREAS, AS POSSIBLY UP TO 25 DEGREES BELOW NORMAL IN
THE ANTELOPE VALLEY AND THE MTNS. IN FACT, SOME DAILY LOW MAXIMUM
TEMPERATURES MAY BE RECORDED ON SAT.
MODELS CONTINUE TO INCREASE RAINFALL TOTALS ACROSS THE REGION, AND
IT NOW LOOKS AS THOUGH THERE WILL BE WIDESPREAD TOTALS OF ONE
THIRD TO TWO THIRDS OF AN INCH, WITH LOCAL TOTALS UP TO AN INCH
FROM SOUTHERN SBA COUNTY THRU CENTRAL AND NORTHERN VENTURA COUNTY
AND POSSIBLY INTO WESTERN L.A. COUNTY.
SNOW LEVELS BE BETWEEN 4500 AND 5500 FEET SAT, AND SEVERAL INCHES
OF SNOW MAY FALL AT ELEVATIONS ABOVE 5500 FEET. WINTER WEATHER
ADVISORIES MAY HAVE TO BE ISSUED FOR THE MOUNTAINS. AT THIS
POINT, IT APPEARS THAT SNOW LEVELS WILL BE TOO HIGH TO BRING
ANY SIGNIFICANT SNOW ACCUMULATIONS TO HIGHER PORTIONS OF
INTERSTATE 5 NEAR THE GRAPEVINE.
THE UPPER LOW WILL MOVE ACROSS NEVADA SAT NIGHT AND EARLY SUN,
THEN INTO NORTHERN UTAH SUN AFTERNOON. SKIES WILL LIKELY BE
PARTLY CLOUDY ACROSS THE AREA SUN, BUT IT LOOKS AS THOUGH ANY
WRAPAROUND SHOWER ACTIVITY WILL REMAIN NORTH AND EAST OF THE
REGION. WITH DECENT HEIGHT RISES, DECREASING ONSHORE GRADIENTS
BETWEEN KLAX AND KDAG, AND SOME INCREASE IN NORTHERLY GRADIENTS,
THERE SHOULD BE SIGNIFICANT WARMING IN MOST AREAS SUN, THOUGH MAX
TEMPS WILL LIKELY STILL BE BELOW NORMAL.
LONG TERM (MON-THU)
25/453 AM.
AN VORT MAX DROPPING SOUTHWARD ON THE BACKSIDE OF THE UPPER LOW
WILL KEEP A TROUGH IN PLACE OVER THE REGION SUN NIGHT/MON. THIS
SLOW DOWN THE WARMING TEND, THOUGH MAX TEMPS MON WILL LIKELY BE AT
LEAST A COUPLE OF DEGREES HIGHER THAN THOSE ON SUN IN MOST AREAS.
UPPER RIDGING WILL BRING MORE SIGNIFICANT WARMING TO THE REGION
TUE. SKIES SHOULD BE MOSTLY CLEAR. HIGHS WILL LIKELY RISE INTO
LOWER 80S IN THE WARMER VALLEYS AND UPPER 60S AND 70S ELSEWHERE.
HEIGHTS WILL BEGIN TO LOWER WED, AND ONSHORE FLOW WILL INCREASE,
SO SOME COOLING IS EXPECTED WED, ESPECIALLY IN COASTAL AREAS.
LITTLE CHANGE IN MAX TEMPS EXPECTED ON THU AS HEIGHTS REMAIN ABOUT
THE SAME.
AVIATION
25/1157Z.
AT 1120Z AT KLAX, THE MARINE LAYER WAS AROUND 4500 FT DEEP. THE
TOP OF THE INVERSION WAS AROUND 5800 FT WITH A TEMPERATURE OF 5 C.
HIGH CONFIDENCE IN TAFS FOR KPMD AND KWJF.
AN UPPER LEVEL LOW IS SET TO IMPACT THE REGION. FLIGHT CATS MAY
FREQUENTLY VARY AT TIMES (VFR, MVFR) WITH SEVERAL CLOUD DECKS
POSSIBLE. SHRA/RA CHANCES WILL SPREAD FROM WEST TO EAST TOWARDS
END OF FCST PD.
KLAX...MODERATE CONFIDENCE IN 12Z TAF. FLIGHT CATS MAY
FREQUENTLY VARY AT TIMES (VFR, MVFR) WITH SEVERAL CLOUD DECKS
POSSIBLE. SHRA/RA CHANCES AFTER 09Z SAT. THERE IS A MODERATE
CHANCE FOR EAST WIND COMPONENT REACHING 8 KTS FROM 12Z TO 17Z
SAT (+/- 1 HOUR).
KBUR...MODERATE CONFIDENCE IN 12Z TAF.
MARINE
25/756 AM.
LOW TO MODERATE CONFIDENCE IN FORECAST.
FOR THE OUTER WATERS, SMALL CRAFT ADVISORY (SCA) CONDS ARE NOT
EXPECTED TODAY. THEN, THERE IS A 20% CHANCE OF SCA LEVEL W-NW WIND
GUSTS LATE OVERNIGHT FRI INTO SAT FOR WESTERN PORTIONS OF
PZZ673/676. THERE IS A 30% CHANCE OF SCA LEVEL WIND GUSTS FOR
WESTERN PORTIONS OF PZZ676 DURING AFTERNOON/EVE HOURS ON SAT.
WIDESPREAD CHANCES FOR SCA CONDS INCREASE (60-80%) SUN AFTERNOON
THRU AT LEAST TUES NIGHT.
FOR THE INNER WATERS NORTH OF POINT SAL, CONDITIONS ARE EXPECTED
TO REMAIN BELOW SCA CRITERIA TODAY, THEN A 20-30% CHANCE SAT
AFTERNOON/EVE. POTENTIAL FOR WIDESPREAD SCA WINDS INCREASES DURING
AFTERNOON/EVE HOURS SUN THRU TUES (50-80% CHANCE).
FOR THE INNER WATERS SOUTH OF POINT CONCEPTION, CONDITIONS ARE
EXPECTED TO REMAIN BELOW SCA LEVELS TODAY. THERE IS A 30-40%
CHANCE OF SCA LEVEL WINDS ACROSS THE SANTA BARBARA CHANNEL DURING
THE AFTERNOON/EVE HOURS ON SAT. THEREAFTER, CHANCES INCREASE TO
>80% ACROSS THE SBA CHANNEL ON SUNDAY, INCLUDING NEARSHORE. THERE
IS A 60% CHANCE OF SCA LEVEL WINDS FOR WESTERN PORTIONS OF SBA
CHANNEL MON AFTERNOON/EVE. MUCH LOWER CHANCES ON TUE.
ACROSS THE WATERS, RAIN IS FORECAST TO BEGIN AS EARLY AS TONIGHT
AND IMPACT THE WATERS FROM NORTH TO SOUTH THROUGH AT LEAST SAT
NIGHT, WITH A SLIGHT CHANCE OF THUNDERSTORMS SAT IN THE INNER AND
OUTER WATERS ALONG THE CENTRAL COAST. ANY THUNDERSTORM CAN PRODUCE
GUST, ERRATIC WINDS, LIGHTNING, AND SMALL HAIL.
LOX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...MW/DB
AVIATION...BLACK
MARINE...BLACK/LEWIS
SYNOPSIS...MW/DB
WEATHER.GOV/LOSANGELES
EXPERIMENTAL GRAPHICAL HAZARDOUS WEATHER OUTLOOK AT:
HTTPS://WWW.WEATHER.GOV/ERH/GHWO?WFO=LOX
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